I don't know if you have found further information by now but I am now living in Maine and was at Columbia Falls, Columbia, Centreville, and Addison ME yesterday looking for cemeteries and family houses/ farms.
I have a copy of Lillian Avery's 1932 book " A Geneology of the Ingersoll Family in America". It is a wealth of information.
Many of the old houses are still in existence and a number of Ingersolls still live in Addison. The small cemeteries have many Ingersoll grave stones and I have made photos of some. I have so far Samuel and his wife, William and his wife, several of the Nathanials. I must go back to finish the other locations. I live 2 1/2 hours away.